Secret-service telephone system.



No. 698,386. Patented Apr. 22, 1902.

E -A. K. ANDBIANO.

SECRET SERVICE TELEPHONE SYSTEM.

A lication filed Jan. 23, 19o1.

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No. 698,386. Patented Apr. 22, I902.

A. K. ANDBIAND.

SECRET SERVICE TELEPHONE SYSTEM (Application filed. Jan. 23, 1901.) (No Model.) s 3 Sheets-Sheet 2.

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ALBERT K. ANDRIANO, OF SAN FRANCISCO, CALIFORNIA.

SECRET-SERVICE TELEPHONE SYSTEM.

SPECIFICATIQN' forming part of Letters Patent No. 698,386, dated April 22, 1902.

Application filed January 23, 1901. Serial No. 44,349. (No model.) 4

T0 64% whom it may concern.-

Be it known that I, ALBERT K. ANDRIANO, a citizen of the United States, residingin the city and county of San Francisco and State of California, haveinvented a new and useful Improvement in Secret Service Telephone Systems, of which the following is a specification.

This invention relates to improvements made in meansfor connecting a number of telephones in one system on what is commonly known as the interconnecting plan, in which every station in the system is provided with means for selecting and switching onto the line of another station without employing a central station and an operator.

The invention has for its object mainly to prevent a party at a third station from getting on the lino and listening to the conversation between two stations already connected through their switching means, thereby providing a secret service between two stations as long as they are thus connected together.

To this end and object my improvements consist in certain novel parts and combination of parts, as hereinafter described, and pointed out in the claims at the end of this specification, in which reference is had to the accompanying drawings, forming part thereof.

Figure 1 represents in front elevation a selectingandswitchingmechanism constructed in accordance with this invention and adapted to a wall-telephone for an interconnecting system, the front of the box being removed and the parts in the position they hold when the receiver is hung up. Fig. 2 is an elevation showing the position of the parts after the receiver has been removedfrom the hook preparatory to selecting and switching onto the line of another station. Fig. 3 is a similar View representing the position of the parts after the switch-arm has been moved 01f the home station and the receiver removed from the hook. Fig. 4 is a vertical transverse section through the arm of the telephone-hook and the hold-oft lever of the circuit-closing device, the section being taken through those two parts on the left-hand side of the circuitclosing spring in connection with which they operate. Fig. 5 is a similar section taken through the telephone-hook at a point to the left of the locking-detent that prevents the switch-arm from being moved off the line until the receiver is removed from the hook. Fig. 6 is a detail view, on an enlarged scale, of the hold-off lever and the armature of the controlling-magnet. Fig. 7 is a diagram illustrating the lines and bell-circuits of three stations interconnected according to this system.

All the stations in this system are interconnected in the well-known manner through line-wires a and a switch composed of stationary contacts I at every station and a movable switch arm or contact d, through which the local circuit e of the receiverfand the transmitter g of the station is connected with the outgoing line. The talking-circuit is connected through this switch with another selected station by a line-wire connecting the two stations and through a Wire connected to the common ringing-battery 70. The primary and secondary circuits, in which are included the receiver and the transmitter and the induction-coil, are connected by contact-springs n p and the arm 5 of the telephone-hook with a line "5, running to one side of the common ringing-battery. Under the ordinary arrangement of these contacts and circuits as heretofore employed when two stations were connected through their switches a third person could get on the line by moving the switch of his station from one line-contact to another until the line in use was obtained, and in that way the conversation between the two connected stations could be overheard unknown to the persons talking.

In the present system the primary of the induction-coil is opened or closed through its battery in the usual manner by the movements of the telephone-hook, so as to prevent battery exhaustion when the telephones are not in use; but the secondary of the inductioncoil, which includes the receiver, instead of being closed on or connected with the outgoingline of the instrument willbe opened when the receiver is taken off the hook and cannot be closed if in the meantime the switch-arm has been moved and stands OK the home contact of the station unless after the switch is moved acircuit can be established through the ringing-battery and the bell-signal at the other station connected through the switch. Under that arrangement of the circuits this can be done only when the switcharm of the time being an isolated and secret service be-- tween one station and another, while it does not interfere with switching and signaling between two stations not already in use. This is carried out and accomplished in a simple and effective manner by the following arrangement of circuits and mechanism.

Referring to Fig. l and to the diagram Fig. 7, 2 indicates an electromagnet in one side of the ringing-circuit between the push-button 'm and the battery is. 3 is an armature pivotally attached at 4, and 5 is a lever working loosely on a pivot I having two arms or members, one of which extends alongside and in front of the arm of the telephone-hook and under the outwardly-bent end of the circuit-closing springp, while the other member, extending downwardly from the pivot, engages a pin 7 on the pawl 8 of the switch-arm (I. That pawl holds the switch-arm against the reactive force of its spiral spring 9 by engaging the ratchet-teeth 10 on the hub of the arm as that part is moved on its center post 12. As the switch-arm is moved 0% the first one of the line-contacts b, which is the home contact in every instrument, thespring 9 is put in tension, and the pawl holds the arm on the switchcontact. On hanging up the receiver the pawl is thrown out of the ratchet-teeth by a tripping-bar 19, pivotally attached to the arm on the hook and set to contact with and press down the outer end of the pawl as the hook moves downward. This is the well-known means employed to throw 01f the pawl and let the switch-arm return to home contact. A spring 21 on the arm of the hook, resting on top of the end of the leg 19, holds that part in perpendicular position, so that the lower end thereof will strike the inner end of the pawl as the hook descends, while in the upward movement of the hook the foot of the tripping-bar will yield laterally and pass the end of the pawl in the usual manner.

13 is a pivoted latch with a hook-shaped lower end engaging the ratchet-teeth from the opposite side of the center and with an angularly-set arm 14 extending upward from the pivot, and 15 is a stop on the arm of the hook, against which the latch-arm 14 is held by a spring 16. These parts are so adjusted that as long as the arm of the hook remains down under the weight of the receiver, as shown in Fig. 1, the hooked end of the latch 13 is held in the ratchet-teeth of the switcharm; but when the receiver is removed and the hook is allowed to rise the stop 15 throws the latch 14 away from the ratchet-teeth and from the lower outwardly-bent end of the eontact-springp, as represented in Fig. 1, and the arm of the telephone-hook is free to touch and close the circuit between the contacts n p as long as the switch-arm is left on the home contact. On the other hand, a slight upward movement of the lever 5 will press up the contact p and hold it away from the arm of the hook, so as to break the circuit at that point as the hook rises.

The upward movement of the outer end of the lever 5 is produced at such time by the pin 7 on the pawl 8 pressing against the bent lower end of the lever as the pawl rises, and such movement takes place as the switch-arm Z) is moved off the stationary home contact. Theoperation of this circuit-breaking lever 5 is electrically controlled also by an armature-lever 3 and an electromagnet 2, the arrangement and operation of which will be understood from Figs. 1, 2, 3, and 6. The armature-lever is pivoted at 4, with its upper end in close relation to the poles of the magnet and its lower end extending alongside the outer end of the lever 5. A pin 17 on that end of the armature-lever projects to the front and under the lever 5, which is reduced in thickness at that end to produce or leave a shoulder back of the outer end. In that position of the armature where it stands away from the magnet, asshown in Fig. 3, the pin 17 rests under the thicker portion of the lever 5 and off the shoulder, thereby holding the lever 5 up against the spring p; but in the opposite position assumed by the armaturelever under the attraction of the magnet the pin17 drops off the shoulder of the lever, as shown in Fig. 2, and allows the springp to contact with the arm of the hook. A coiled spring 18, attached to the armature-1e ver and to the lever 5, acts to draw the armature away from the magnet when the current is cut off and serves'to hold the lower end of the armature-lever up against the lever 5 in either position as that'end of the lever 5 is raised or lowered by the contact of the stud 7 with the bent end. In that position of the last-mentioned lever which allows the contact-spring p to touch the arm of the hook and close the circuit the pin 17 lies on the shoulder and off the thick portion. In that position it is held by a brake-rod 23, pivotally attached at 24 to a fixed support, such as :the bracket that carries the switch-arm and its pawl, and with the upper end lying against the back of the armature and the opposite end resting against a pin 25 on the switch-arm. A spring 26, attached to the upper end of the rod, holds the lower end always up to the stop-pin 25, thereby causing that end of the rod to follow the movements of the switch-arm and causing the upper end to press and hold the armature up to the magnet when the switch-arm is set to the home contact, but to move away from the armature and allow that part to be drawn back by the spring 18 as soon as the switcharm is moved to another contact in the row I).

The function or purpose of the rod 23 is to prevent the pin of the armature-lever from holding up the lever 5 against the spring 1) and breaking the circuit when the receiver is removed from the hook, provided the switcharm is not moved off the home contact. Arranged in this manner with relation to the parts of the two switches the arm 5 is held mechanically away from the contact-spring 1) while the receiver is on the hook and the arm is clear of the two contact-springs n p, and, on the other hand, when the receiver is removed the arm of the hook flies up and closes the circuit between the springs, provided the switch-arm has not been moved away from the home contact. In the one case the instrument is on its ringing-circuit ready to receive a call, because that circuit is closed in the usual manner through the two contact-springs behind the hook, and in the other case the local or primary circuit is closed through the contact springs n 19. Should the switch-arm be moved olf the home contact at that time, however, the pawl 10 lifts the upper end of the arm 5 and allows the spring 18 to draw the end of the armature-lever away from the shoulder and under the thicker portion of the lever, thereby lifting the contact-spring p and holding the circuit open. The rod 23 being released by the movement of the switch-arm at that time is drawn away from the armature-lever by the coiled spring, and consequently the instrument is cut 01% from the outgoing line and is inoperative until the magnet acts to attract its armature and allow the contactspring to get the hook-arm. The magnet being interposed in the ringing-circuit, as already described, will become energized when the circuit is closed at the push-button ifa circuit can be established through the ringing-battery and the bell-circuit of the other station,which can only be done when the receiver is on the hook and the switch-arm is on its home contact at that station. The relation of the talking and ringing circuitsestablished between two connected stations at such time will be understood by referring to the diagram Fig. 7, in which station No. 1 is represented as being connected to station No. 3 for conversation. At the time of connecting withand calling the latter station the switch-arm of station No. l ismoved and set to the third one of the switch-contacts, and as the receiveratthe calling-station was removed from its hook before the switch. could be made the arm of the hook is not in contact with springp and the talking-circuitis broken at that point. If, however, the switch-arm of stationNo. 3 is on its home contact and the receiver is on the hook, the magnet 2 at station No. 1 can be energized by pressing the button m, thereby attracting the armature-lever and allowing the pin in its lower end to set under the narrow part of the lever 5, allowing the contact-springp to touch the arm of the book. When the parts are in the position above described, the circuit between the magnet and the ringing-battery is completed by pressing the button m and closing the circuit from one side of the battery through the wires h, in which is included the magnet 2, the push button contacts, the frame that supports the pivot of the hook, the movable contact at, the third stationary contact b, and the line a, which connects that contact with the home contact at station No. 3. From that contact the circuit is through the switch-arm d, the frame that carries the pivotof the hook at the latter station, thence through the wires connecting the two front springs of the push-buttons m and through the back springs 27 28 to the bell, and thence through the wire connecting the bell of station No. 3 with the other sidet'of the ringingbattery. By this means the talking-circuit at station No. l is closed at n p by the telephone-hook when the push-button at that station is pressed. No signal will be transmitted at that time, however, to another station, as station No. 2, for illustration, because the circuit required to ring the bell of that station can only be established through the contact belonging to that station in the row of contacts b at station No. 2, on which the switch-arm of the last-named station has been set, and as the arm cannot be moved without first taking down the receiver of station No. 2 the bell-circuit and the electromagnet 2 in that circuit are cut off from the ringing-battery, in consequence of which the bell will not ring and the lever 5 will not be set away from tne contact 12.

From the foregoing descriptionit will be seen that the system embraces the following essential features: first, at each station alocal switch comprising individual line-contacts and a movable contact connecting by adjustment the receiver and transmitter-circuit of the station with another station through the line-contact, the local primary circuit being connected to the line by the act of taking down the receiver, provided the movable contact of the switch is standing on its home contact; secondly, a ringing-circuit including a main battery common to all the stations and a local bell-circuit including a push-button at each station, by which a circuit is completed between the calling-station and the bell circuit of the called station through the individual line-wirebetween the stations and the main battery when the mov- &

able contact of the called station is on its own line, and, thirdly, electrically-actuated means controlled by or through the ringingcircuit established between two stations and operating to break and hold open the primary circuit of the calling-station when a switch is made, butto close that circuit for use if the ringing-circuit can be established between the two connected stations by pressing the push-button at the calling-station.

Having thus fully described my invention, What I claim as new therein, and desire to secure by Letters Patent, is

1. In a telephone system, stations interconnected through individual lines and local switches,including a line-contact for each station and a movable contact adapted to connect the primary circuit of the station with the line of a selected station; means controlling the movable con tact to hold it normally on the line-contact of its own station while the receiver is hung up and to release it for switching when the receiver is taken down; a ringing-circuit common to all the stations connecting one station with another through their respective switching-contacts to form with the interconnecting lines of two stations a metallic circuit including a main battery and a bell and push-button at each station; means controlling the talking or secondary circuit to open and close the same, and itself controlled by the movable contact; and electrically-actuated means in the ringing-circuit between the main battery and the push-button adapted to throw said controlling means out of action when a circuit is completed through the main battery and the circuit of the called station.

2. In a telephone system the combination, with a plurality of stations interconnected through individual line-wires, and switching devices at each station comprising stationary contacts and a movable contact through which the talking-circuit of the station is connected with another selected station; of a ringing circuit controlling the telephone switch-contact of the talking or secondary circuit and including a main battery and a push-button at every station, and electricallyactuated means in the ringing-circuit at every station controlling the talking or secondary circuit, said means being controlled by the movable contact of the switching device, whereby the primary circuit is broken and held open when the movable contact is moved off the individual line-contact of the station, and is closed when a ringing-circuit can be completed between the two connected stations.

3. In a telephone system containing stations interconnected through local switching devices and line-wires, the combination of means controlling the talking, or secondary, circuit at each station, said means being controlled by the switch device to break or hold open the primary circuit when the switch is moved off its home contact; stringing-circuit including a main battery and a push-button at each station, by which a circuit is completed through the battery and the bell at the called station; means controlled by the mov able contact for breaking said circuit when the movable contact of the station is moved off its line-contact; and means operative electrically from the main battery over the ringing-circuit and line-wires from the calling-station through the called station to throw the controller of the calling-station out of action and restore its talking or secondary circuit to the line for operation.

In testimony that I claim the foregoing I have hereunto setrmy hand and seal.

ALBERT K. ANDRIANO. [L. s] WVitnesses: v

EDWARD E. OSBORN,

M. REGNER. 

